Showing posts with label scientific method. Show all posts
Showing posts with label scientific method. Show all posts

Monday, 18 February 2008

Question 5: Good luck or good management? Part Three.

A quick summary of parts one and two.

(I could pretend this is for the benefit of the reader but it is mainly because I've been very lazy updating the blog and need to remind myself what I'm talking about)

Important point number one: You cannot dismiss a model on subjective grounds. A model is not less valid because you (or any number of other people) do not like it. A model is not less valid because it contradicts a piece of dogma or accepted wisdom. A model is not less valid because it appears to be complicated. A model is not less valid because it appears counter intuitive.

Important point number two: The scientific method is objective and is open to everybody. There is no grand conspiracy within 'science' to exclude particular beliefs or ideas. The criteria for a scientific model are objective and do not depend upon the prejudices of the existing scientific community. If a model can be clearly expressed and can be tested then it is, in the broadest sense of the term, science. If the model is useful (by my slightly non-standard definition of the term) then it is good science.

Good luck or good management?

Back to the post title and back even further to my earlier definition of God.

One of the fundamental characteristics of God is the role of creator. The assertion of the Old Testament is that, in some sense and to some degree, everything that currently exists was created by God. I want to avoid a discussion of the interpretation of Genesis and the specifics of how and when that creation took place and examine whether it is possible to prove or disprove the role in more general terms. Is there a role in our understanding of the observable universe that requires a conscious creator?

An aside on simplicity: in Important Point 1, I dismissed the idea that simplicity should be a guide to the validity of a model, but I'll dip into it briefly anyway. I'm nothing if not inconsistent. A seemingly simple explanation for any complicated observation is "God did it". It is certainly short and pithy, but that is not the same as simple. The explanation "God did it" is only simple if we assume a priori that God exists. If you do not make this assumption, then the explanation for something complicated becomes "Something even more complicated did it." Which is hardly satisfactory. If you combine it with the common reasoning that God must exist because complicated and amazing things exist, then the argument becomes circular: How do you explain the complexity of the universe? God did it. How do you know God exists? Because the universe is complicated.

A conscious creator in science.

None of the current set of models for how we came to be here include a role for a conscious creator. The model of natural selection does not require any intelligent and deliberate input to explain the evolution of the current gamut of life on earth. The stars and planets do not require a conscious hand to explain their positions and movements. To my knowledge, there is no common scientific model for anything that requires a creator.

This is not a concerted and deliberate omission; science has arrived, over the course of a couple of centuries of subjective application of an objective method, at a set of models that simply do not require a creator. There is no gap in the models that can be usefully and testably filled by a creator. The models do not match with observation better if you include a creator somewhere within them.

Now ... science does not know everything. But it can, in principle, model anything, and everything that science has currently modelled works perfectly well without a creator. There is no evidence and, more importantly, no need for a creator.

We are here, to the very best of our understanding, entirely by accident.

Wednesday, 6 February 2008

Lemma 3: science is objective

I made the distinction in the previous post between 'subjective' and 'objective' when judging the merit of an idea. A valid question is whether a judgement made by humans can ever be truly objective. Humans are fallible and they have selfish agendas and moral beliefs and all manner of prejudices and tastes. An individual scientist can clearly make errors of judgement and can be influenced by his or her own beliefs. Why does an assertion that has been scientifically tested have more value than one that has not?

The answer is in the title. Individual scientists are not necessarily objective, but science and the scientific method are. There is no magic to the scientific method: you come up with an idea, you present that idea in an understandable and testable form, you test the idea against observation and you allow anybody else in the world to test it as well. Science is a group activity open to anybody who has the capacity to learn the language and the methods. There are no sacred cows: any idea can be challenged.

Now ... the scientific community (like society in general) is fairly conservative. When somebody comes along with an observation or a model that challenges the current consensus, it will be greeted with scepticism. But the history of science contains a huge number of minor and major revolutions. Better ideas always win in the end. Our current model of the universe is quite clearly better than it was a century ago.

A conspiracy theorist could argue that the entire scientific community is either deliberately or accidentally misleading itself. But there is nothing unique about scientists and nothing in the scientific method to exclude a specific group or belief. This argument is essentially saying that the entire human race is misleading itself. If you think that science has made a grave mistake, then politely knock on the door and put them right. Copernicus did it. Einstein did it. It is not a closed shop.

Are scientists 100% objective? No. Is every scientific conclusion 100% objective? No.

Are ideas that have been posed and tested via the scientific method more objective than those that have not: absolutely yes.

Thursday, 31 January 2008

Question 5: Good luck or good management? Part Two.

In part one I argued that you cannot dismiss a model because it feels unlikely, and you cannot choose one model over another purely on the grounds that it appears less complicated. Something does not become a valid explanation simply because you like it and want it to be true. The observable behaviour of the universe is not subject to human whims and tastes.

(note: the observable behaviour of the universe is subject to human fallibility, see
Observer Effect. Quite often the mere act of observing something has an effect on its behaviour. More on that when I get back to omniscience ... just in case Robin is about to pre-empt me again.)

To decide the value of a model you have to objectively test it. The model has to make useful predictions that can be tested against observation. This is an absolutely critical step in the scientific method: your ideas must be expressed in such a way that other people can test them and demonstrate that they do not work. One of the primary reasons for publishing a scientific model is to allow your peers to explain why it is rubbish and, hopefully, propose an alternative and better model in its place.



"The earth is the centre of the universe."


The Geocentric Model (the idea that the earth is a sphere at the centre of the universe and everything else revolves around it) was essentially the first scientific model for how the universe works. It matches quite well with casual observation: the earth does not feel like it is moving and the sun and the moon and the stars appear to revolve around it. Unfortunately, it does not match with closer examination: if you accurately map the position of the stars and planets in the sky, they do not move in the way that a geocentric model predicts they should.

The ancient Greeks and later astronomers dedicated a great deal of effort to modifying and elaborating on the geocentric idea to create a model that did accurately predict the movements of the heavens. Unfortunately, they were hampered by a single assumption: the earth is the centre of the universe. It was only when Copernicus dared to suggest that this assumption was false and that
the earth was actually revolving around the sun that a simple model suddenly started to match observation. This led to a fairly dramatic conflict between the scientific method and doctrine: according to the scientific method this was a useful and accurate model of the universe, but according to common belief (and Christian dogma) this was heresy.

Science has since established that not only is the Earth not the immovable centre of the Universe, neither is our Sun, or even our galaxy. In fact, a conventional idea of an immovable centre of the universe may not even make sense.

"Space and Time are absolute"


Isaac Newton came up with a set of models for how objects interact (laws of motion and gravity) that formed the basis of classical mechanics. It is impossible to overstate just how clever Newton was and how important these theories are: very very very. Unfortunately, as in the geocentric model, Newton's model makes some assumptions that mean it is only useful in particular contexts (wiki link not necessarily for the faint hearted). As I claimed earlier, this does not make the model 'false', it just puts limits on when it can be used. It is still very very very useful.

Towards the end of the 19th Century, scientists began to make measurements that did not quite match with the predictions of Newton's model. In the early 20th Century, Einstein proposed alternative models (Special and subsequently General Relativity) that better matched the new observations. In this instance, Newton's model was not supported by quite such a firm religious doctrine as the geocentric model, but there was still some resistance. Newton's model is more intuitive and it had been around for a long time. People liked it. But (how hard can I bang this particular drum?) the value of a model is not measured by subjective popularity, it is measured by objective testing. At large scales and great speeds, the predictions made by Einstein's model are objectively more accurate than those made by Newton's model. The scientific method insists that you choose the better model for the job.

(note: there were, and still are, dogmatic objections to Relativity, but they are not anywhere near comparable in scale to the objections to Copernicus' suggestion that the earth revolves around the sun)

Final bang of the drum: the scientific method does not care what people like or what existing doctrine or tradition says. A model is only as good as the evidence that supports it. Badum tish.

Friday, 25 January 2008

A further interlude: a bit on truth

Having promised myself not to get involved in any instant coffee student philosophy discussions, I'm going to have to tread quite carefully around this. But Robin poked me on the subject and it does merit some thought. This still officially counts as an interlude ... I am loathe to attempt to formally define or question the concept of 'truth'. And I have previously stated that for current purposes, I'm assuming science is not a list of absolute facts (or truths).

The earth is flat.

What do we mean when we say something is true or false? I mentioned the flat earth model earlier so let us start with that. The statement "The earth is flat" is definitely false. (False is much easier to spot than true.) Here is a collection of photos of the earth taken from space. Conspiracy theorists may wish to dispute their veracity ... but not with me. Thanks all the same.

A flat earth model is very useful if you are building a house, but architects using the flat earth model know that the earth isn't actually flat. I hope.

What about the statement "The earth is round"? If you were pedantic to the point of being antisocial, you might argue that strictly speaking the earth is an oblate spheroid and not perfectly round at all. Is the statement still true? It's fairly accurate. It's probably the best single syllable description of the shape of the earth. It's not as if 'round' is a strictly-defined geometric term in any case. Biscuits are round. People's heads are round. Round-ish.

So in common usage 'true' and 'false' are not absolute black and white concepts.

The earth is 7000 years old.

Some biblical literalists use the creation stories in the Old Testament to assert that the earth is only six or seven thousand years old. Some will even couch this assertion in scientific terms and claim it can be supported by a legitimate use of the scientific method. A quick google will bring up a number of such papers.

This assertion is false. Uncontroversially and incontrovertibly false. This model of the earth's history is contradicted by a truly massive weight of evidence. It is as easily falsifiable as the suggestion that the earth is flat.

Note that this does not instantly disqualify it from being a scientific model. As I said earlier:

"Scientific models and theories are not 'true' or 'false'. They are 'useful' or 'not useful' in particular contexts."

and

"Science is a set of well-defined models that can be tested against observation."

If you can find a context where the assumption that the earth is 7000 years old has an application, and you can express it in terms that allow it to be tested against observation in that context, then it will become a useful scientific model.

I will buy an iPod for the first person who can give me an example of a context where this assertion is useful and a method for testing it. Any size and colour you like. The answers "to prove the literal truth of Genesis" and "by reading the word of God" will receive a mystery booby prize.

So ... being demonstrably false does not stop something from being science; failing to satisfy the simple criteria of a scientific model and not applying the scientific method stops something from being science.

I have no idea if this satisfies Robin's qualms about "true" versus "useful". I'm sure he'll tell me.

Thursday, 24 January 2008

A light-ish interlude.

OK. The last entry was possibly a step and a half. And the final assertion that "nothing that exists is 'outside' science" is something of a brainful. So this post is a gentle meander around the idea until I'm happier with it.

Bud has made an interesting comment:

"... modeling anything with science is, in itself, a leap of faith"

This is worth dwelling on. It's an important part of understanding the difference between the scientific method and a scientific model, and between a model and reality itself.

A model is a leap of faith. You are being asked to accept that what the model tells you is the same as what you would experience in Real Life. Take the seemingly simple example of numbers and arithmetic. As a young child, you are taught to accept that the sum "5 + 3" is comparable to adding five apples to three bananas. You are asked to believe that every single time you bring together five apples and three bananas they will always combine to make eight pieces of fruit.

This is a leap of faith or an act of belief. See the previous posts on belief in science and a belief in belief.

Two things turns this act of belief into a scientific model. Firstly, the model is expressed in a way that is comprehensible and useful. The vast majority of human beings can be taught basic numeracy and can apply it in extremely useful ways to Real Life. Secondly, the model is expressed in such a way that it is testable. We can compare the results that the model of numbers and basic arithmetic give us, with the results that we observe in Real Life. We can go out and buy five bananas and three apples and we can put them together and count them and (fortunately for us) every single time we will count eight pieces of fruit.

Pure Mathematics

While we're meandering and talking about arithmetic, let us take a brief stroll through the scented meadows of Pure Mathematics. Some people don't even label pure maths as a science. Even the term 'pure' has a strange, un-sciency feel to it. Here's what wikipedia has to say about it:

"Broadly speaking, pure mathematics is mathematics motivated entirely for reasons other than application."

Which is more a definition of what it isn't than what it is. Essentially, pure maths takes the 'useful' part of our definition of a scientific model and puts it to one side. It still takes a model and expresses it in comprehensible terms (comprehensible to other pure mathematicians, that is), but it does not care whether the results are applicable to the Real World.

Let's take the schoolboy favourite concept of an infinite number. There is a finite amount of 'stuff' in the universe. So the concept of an infinite amount of something is, to all intents and purposes, entirely useless. At the same time, it is an extremely cool idea (well ... to pure mathematicians and schoolboys at least). Pure maths is built upon piles and piles of extremely cool but generally useless things.

There are of course exceptions. The simple ends of pure mathematics are useful: numbers and geometry for example. Many other abstract and 'pure' mathematical models have turned out to have application in the Real World, although typically they become useful decades or centuries or even millennia after they are first investigated 'for fun'.

Intuition

Intuition is great. The human brain has the capacity to observe the world and make lightning fast decisions about what is happening and what is likely to happen. We can throw and catch a ball without performing any complicated calculus to work out its trajectory. We can distinguish between faces and voices from objectively tiny differences. We can store and recall and relate information about things with unlikely speed.

But intuition has a very definite limit. The human brain works on a human scale. If you go very far outside that scale, either very much bigger or very much smaller, then intuition falls down. Things become quite literally 'strange'.

Take symmetry as an example. Symmetry is an intuitive concept. Imagine you take a square of plain white paper and place it in front of you. You can turn it through a quarter, a half, or three quarters of a turn (90°, 180°, 270°) and it will appear the same. You can reflect it in a mirror and it will still appear the same. It has some symmetry.

Now, I used the word "imagine" there for a reason. You don't actually have to take a square of paper. You know these things from experience and intuition. You've seen a square before. You know how squares work. You can imagine the same process with a rectangle or a triangle or any number of familiar shapes and you would understand how their symmetry worked.

There is a simple model of symmetry in a branch of pure maths called Group Theory (no wiki link as it would confuse more than anything else). It provides a formal model for what we understand intuitively about symmetry. But, because it is pure maths and not bounded by a need to relate to the Real World, it goes some steps further and provides a formal model for aspects of 'symmetry' that are utterly outside our intuitive understanding. It can, for example, model the idea of an object that needs to be turned around twice (720°) before it looks the same. Clearly, that makes no sense at all for our intuitive understanding of the physical world.

Except (either beautifully or irritatingly, depending on your perspective), there is an application for this bizarre and unintuitive model in Quantum Mechanics. It is counter intuitive because it is not on a human scale, but it is still useful. And I'm definitely not linking to the wikipedia article here since the page acknowledges itself that "All or part of this article may be confusing or unclear."

So:
  • a scientific model is a leap of faith: the scientific method requires you to TEST the model
  • pure maths is only science-ish since it investigates models for their own sake
  • a model does not need to be intuitive to be useful or scientific